If there are no fish in the tank then a water change IMO wouldn't be needed, a test kit would be handy also, most people on here including myself use the API master kit its a little pricey but i'm sure someone from your neck of the woods can give you a website where you would get it cheaper.

As for the plants I cycled my first tank with them in there and they are still fine but i'm sure someone more experienced with the cycle will advise you better than I can :)